1. Field of the Invention
The present invention relates to a method and apparatus for driving a liquid crystal display, and more particularly to a method and apparatus for driving a liquid crystal display capable of changing a brightness of a display picture in accordance with input data information and partially emphasizing the brightness.
2. Description of the Related Art
A liquid crystal display displays pictures by adjusting light transmittance of liquid crystal cells in accordance with a video signal. The liquid crystal display is embodied with an active matrix type having a switching device formed for each cell and is applied to the display apparatus such as a computer monitor, an office automation apparatus and a cellular phone. A thin film transistor (hereinafter referred to as “TFT”) is mainly used as a switching device in the liquid crystal display of an active matrix type.
FIG. 1 schematically illustrates a driving apparatus of the liquid crystal display of the related art.
Referring to FIG. 1, the driving apparatus of the liquid crystal display of the related art comprises a liquid crystal panel 2 in which m×n liquid crystal cells are arranged in a matrix and m data lines D1 to Dm and n gate lines G1 to Gn intersect. A TFT is formed at each interconnection. A data driver 4 supplies a data signal to the data lines D1 to Dm of the liquid crystal panel 22, a gate driver 6 supplies a scan signal to the gate lines G1 to Gn, and a gamma voltage supplier 8 supplies a gamma voltage to the data driver 4. A timing controller 10 controls the data driver 4 and the gate driver 6 by using a synchronization signal provided from a system 20, a DC/DC converter 14 generates voltages supplied to the liquid crystal panel 2 by using a voltage supplied from a power supplier 12 and an inverter 16 drives a backlight 18.
The system 20 supplies to the timing controller 10 vertical/horizontal synchronization signals V sync and H sync, a clock signal DCLK, a data enable signal DE and a data R, G and B.
The liquid crystal panel 2 comprises a plurality of liquid crystal cells Clc arranged in a matrix at the interconnection of the data lines D1 to Dm and the gate lines G1 to Gn. The TFT formed respectively in the liquid crystal cell Clc supplies to the liquid crystal cell Clc the data signal supplied from the data lines D1 to Dm in response to the scan signal supplied from the gate line G. Further, a storage capacitor Cst is formed in each liquid crystal cell Clc. The storage capacitor Cst is formed between a pixel electrode of the liquid crystal cell Clc and a pre-staged gate line or is formed between the pixel electrode of the liquid crystal cell Clc and a common electrode line, thereby maintains a uniform voltage of the liquid crystal cell Clc.
The gamma voltage supplier 8 provides a plurality of gamma voltages to the data driver 4.
The data driver 4 converts a digital video data R, G, and B into an analog gamma voltage (data signal) corresponding to a gray scale value in response to a control signal Cs from the timing controller 10 and supplies the analog gamma voltage to the data lines D1 to Dm.
The gate driver 6 sequentially supplies a scan pulse to the gate lines G1 to Gn in response to the control signal CS from the timing controller 10 to select a horizontal line of the liquid crystal panel 2 to which the data signal is supplied.
The timing controller 10 generates the control signal CS for controlling the gate driver 6 and the data driver 4 by using the vertical/horizontal synchronization signals Vsync and Hsync and the clock signal DCLK received from the system 20. Herein the control signal CS for controlling the gate driver 6 comprises a gate start pulse GSP, a gate shift clock GSC and a gate output enable GOE etc. And the control signal CS for controlling the data driver 4 comprises a source start pulse GSP, a source shift clock SSC, a source output enable SOC and a polarity signal POL etc. And the timing controller 10 rearranges the data R, G, and B supplied from the system 20 to supply the rearranged data to the data driver 4.
The DC/DC converter 14 increases or decreases 3.3 V of a voltage received from the power supplier 12 to produce a voltage to be supplied to the liquid crystal panel 2. The DC/DC converter 14 generates a gamma reference voltage, a gate high voltage VGH, a gate low voltage VGL and a common voltage Vcom.
The inverter 16 supplies a driving voltage (or a driving current) for driving the backlight 18 to the backlight 18. The backlight 18 generates light corresponding to the driving voltage (or the driving current) supplied from the inverter 16 to supply the driving voltage to the liquid crystal panel 2.
In order to display dynamic pictures in the liquid crystal panel 2, the contrast should be clear. However, no method exists that is capable of extending the contrast in accordance with the data in the liquid crystal display of the related art and thus it is difficult to display dynamic pictures. Further in the related art, the backlight 18 of the liquid crystal display constantly and uniformly radiates irrespective of the data. If the backlight 18 constantly and uniformly radiates irrespective of the data, it is difficult to display dynamic and vivid pictures in the liquid crystal panel 2. For example, if an explosion scene is to be vividly displayed, the brightness of the explosion scene should be emphasized. However, since the backlight 18 constantly radiates irrespective of data in the liquid crystal display of the related art, it is difficult to represent the vivid picture. That is, it is impossible to partially emphasize the brightness in the related art.